Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$179.28	7.559%	$192.8318	$192.83	$192.85	$192.80
Purchase #2	$77.85	7.469%	$83.6646	$83.66	$83.65	$83.70
Purchase #3	$112.82	3.223%	$116.4562	$116.46	$116.45	$116.50
Purchase #4	$200.40	13.134%	$226.7205	$226.72	$226.70	$226.70
Purchase #5	$134.75	12.352%	$151.3943	$151.39	$151.40	$151.40
Purchase #6	$176.71	12.382%	$198.5902	$198.59	$198.60	$198.60
Purchase #7	$43.85	4.228%	$45.704	$45.70	$45.70	$45.70
7 purchase totals =	$925.66		$1,015.3616	$1,015.35	$1,015.35	$1,015.40